Manufacture of carbon black



May 10, 1932. c. MILLER 1,857,469

MANUFACTURE OF CARBON BLACK Filed March 12, 1951 INVE NTOR Patented May 10, 1932 entree sra'ras PATENT orrlca CARROLL MILLER, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR '10 THERMA TOMIC CARBON COMPANY, OF YIT'ISBTIBGH, PENNSYLVANIA, A. CORPORATION OF DELA- WARE MANUFACTURE OF CARBON BLAGK Application filed March 12, 1931. Serial No. 521,926.

ment over the process developed by Ellwood B. Spear and described in the Spear application Serial No. 384,650, filed August 9, 1929.

According to the preferred procedure in the Spear process, the hydrocarbon gas to be decomposed isdilutedwith hot gases of combustion furnished by a burning fuel. The mixture of the hot gases of combustion and the hydrocarbon gas is passed over extensive hot contact surfaces to decompose the hydrocarbon gas and yield solid carbon particles.

Part of the carbon thus formed is deposited upon the hot contact surfaces and part is entrained in and swept along with the gas, which is then pamed through devices for quickly cooling it and separating the carbon from the gas.

In the Spear and Moore application Ser. No. 300,131. filed August 16, 1928, is described another process of thermal decomposition of a hydrocarbon gas to produce carbon black in accordance with which a substantially inert diluent gas, preferably the residual gas resulting from the previous decomposition of a quantity of hydrocarbon gas and consisting principally of hydrogen, is preheat-ed above the decomposition tempera ture of the hydrocarbon gas. The hydrocarbon gas to be decomposed is then mixed with the diluent gas; and the mixture is passed over extensive hot contact surfaces to decompose the hydrocarbon gas and yield solid carbon particles.

My improved process as hereinafter more fully described combines advantageous features of both the Spear and the Spear and Moore processes. 1

As described in the Spear and Moore application Serial No. 300,131, filed August 16,

the process described in the said application has certain of the desirable ualities of both the common commercial car on blacks and the Brownlee and Uhlinger carbon black. Generall speaking, the Spear and Moore carbon blac has the low rubber stiffening qualities of the Brownlee and Uhlinger carbon black but has a darker color. It imparts an ultimate tensile strength to cured rubber compositions approximately equal to that imparted by an equal weight of the best grades of common commercial carbon black. It imparts to the cured rubber a greater elongation at the point of rupture than that imparted by equal weights of either common commercial carbon black or the Brownlee and Uhlinger carbon black.

The process, as described in the Spear application Serial No. 384,650, filed August 9, 1929, has, among other advantages, the use of a cheaper diluent gas, and the advantage in operation that the roducts of combustion supply heat to t e mixture, thereby lengthening the period during which the extensive hot contact'surfaces remain at the proper temperature to efliciently decompose the hydrocarbon gas and yield solid carbon particles.

the hydrocarbon gas being decomposed is diluted with a mixture of inert diluent gases formed by mixing with hot gases of combustion residual gas resulting from the previous decomposition of a quantity of hydrocarbon gas. By using such a mixture, a carbon black is obtained having qualities approaching those of the carbon black produced by the Spear and Moore process described in application Serial No. 300,131, filed August 16, 1928; and at the same time the advantages of cheapness of the gases entering into the mixture which is used to dilute the hydrocarbon gas, and the eificiency in operation due to the heat supplied to the mixture by the products of combustion are retained.

My improved process may be carried out in connection either with the apparatus disclosed in the Spear application Serial No. 384,650, filed August 9, 1929, or in connection with my improved apparatus disclosed in application Serial No. 511,709, filed January 28, 1931. a. I will now describe my improved, proces l in connection with the latter type of apparatus. The drawing illustrates the apparatus diagrammatically in central vertical section. Generally speaking, the apparatus co 10 of a heating retort which contains refractory checkerwork, -this checkerwork being arranged to be heated to a high temperature by a heating blast. Periodically, the heating blast is cut ofi, and the hydrocarbon 18 gas to be decomposed, usually natural gal i, to-

gether with diluent gases, are passed ugh the heated checkerwlprlgb and thci1 hydrocarbog gasis ecomposedt ere yinto solid carbon particles. Part the carbon ac particles are deposited on the checkerwork and part are swept along with the gas, which passes out through devices for cooling it and filtering out and recovering the entrained n. v V Referring'to the illustrated embodiment of the apparatus, there is shown a heating retort 1 in which the decomposition, of the hydrocarbon gas takes place. The gas, which issues from the retort and which contains the entrained carbon particles, passes through the'out-let 2 into a chamber 3 into which the water spray 4 is discharged to. cool the gas. The gas is highly heated and converts the water into steam, the latent heat of evaporation serving efliclently to cool the gas. The gas then passes through a. conduit 5 into the lower portion of a separat' where the gas passes through t e fabric'bags 8, which are shaken from time to time to'disbags, receptacles, or the like. The general lay-out as above described is disclosed and claimed in my co-pending application, Serial No. 511,709, mentioned above. The means' for the gas is described in the Brown- -lee and Uhlinger Patent 1,520,115; and the temperature of the coo chamber 3 is prefspaces or chambers16 beneath the checker-v work. Above the checkerwork is a mixing. chamber 17. i

- A conduit 18 opensinto the chamber 16 to 65 supply to the retort 1 a mixture of fuel gas plied tothis passage.

.facing 32 and a backing 33, similarly as in the case of the retort 1. Inthe retort 30 is a chamber 7 4 lodgethe carbon. The carbon falls into thehopper 9' from which it may be discharged from time to time through a valve 10 into duit 18. 'During this preliminary heating, which occurs whena co'ld' retort is to be r erably automatically thermostatically. con-- and air. In this way, a heating blast can be discharged into the chambers 16. The top or dome of the retort is rovided with an ope or passage 19 w ich is normally closed a cap valve 20. a A pipe 22 discharges mto the top of the retort, and to this pipe are connected two supply pipes one of which, No. 23, supplies the ydrocarbon gas to be decomposed, which is commonly known as the run gas in this industry.

' The second branch,'which is shown as a pipe 24, is connected to a storage tank 25 in which the residual gas resulting from the previous decomposition of a uahtity of ydrocarbon gas is confined. e pipe 23 is controlled by a valve 26 and the pipe 24 is controlled by a valve 27. A blower 28 may, if required, be inserted in the pipe 24 to pump gas from the container 25 through the pipe 24'into the retort. Accordingly, run gas alone may be supplied through the pipe 22 into the passage 19; or a mixture of run gasrand residual gas may be sup- A smaller retort 30 is connected to the passage 19 to supply the hot gases of combustion which are tobe mixed with the residual gas and the run gas. The retort 30 has a steel plate casing 31 and a lining consisting of a suitable mass of checkerwork 34. Air is blown or otherwise introduced intothe retort 30 through a pipe 35 controlled by a valve 36. Fuel is supplied through a pipe 37 controlled by ajvalvej38, this fuel with the incoming air and burning in the retort 30. A refractory conduit 40 consisting of a facmg 41' and albacking 42'of refractory insulation material connects, the retort 30 to the op g 0 PaSSage-19.

My improved process is carried" outras follows :The checkerwork 14 is initially heated by a cheatin'g blast 'throughthe conbrought into operation, the gases ofjcdmbustion pass up thro h the checkerwork '14 to initially heat it emfi, Thefcombu stion gases are allowed to escape through theopened cap valve 20 in the top of the retort.

' Aftera cold-retort has been heated up, it

is in condition to operate for the production of-'carbonblack. To do. this the retort 30 is operated to'supplyhot gaseous products of combustion. to the passage 19.: Theproportion of air admitted through the pipe and the fuel gasv admitted through the sup: 7

ply pipe 37 may be adjusted "by manipulation r of the valves in these pipes so-that the products ofcombustion as they-emerge from retort 30 are principallyi or all carbondioxide,

orw principally carbon monoxide or a mixture of carbon dioxide and-carbon monoxide to-' M gather, of course, withj the nitrogen derived? from the air and water vapor from the oxide tion of the hydrogen constituent of the hydrocarbon gas. The efiect of the dlfierent proportions of the carbon diox 1d e and carbon monoxide is discussed in detail 1n the Spear application, Serial No. 384,650.

Through the pipe 22 is introduced into the passage 19 a mixture of run gas (entermg through the pipe 23) and residual gas (entering through the pipe'24) Th s mixture entors the passage 19 and mixes with the stream of highly heated gases of combustion from the retort 30. The run gas, which is usually natural gas and which is now mixed bpth with residual gas and gaseous combustion products from the retort 30, passes down through the checkerwork 14, which has been highly heated by the blast previously applied to it. The volume of residual gas admixed with the run gas may be controlled by the valve 27. The characteristics of the resultant carbon black are influenced by the proportion of residual gas which is employed. If a larger proportion of residual gas is used than of combustion products from the retort 30, a carbon black closely resembling the carbon black obtained by the process described in application Serial No. 300.131 is collected in the chamber 7. If too small a proportion of combustion products is used, the cooling of the checkerwork 14 takes place quite rapidly, the yield of carbon black decreasing as the temperature of the checkerwork falls. If, on the other hand, the proportion of combustion products is materially increased, a carbon black is obtained whose characteristics approach those of the carbon black obtained by the process described in the Spear application Serial No. 384,650. I prefer to supply the products of combustion in the ratio of not less than one part combustion products to four parts residual gas, and not in excess of the ratio or four parts of combustion products to one part of the residual gas.

The total volume of diluent gas, that is the residual gas and combustion products combined, is preferably in excess of the hydrocarbon gas, the volumesof the gases being computed of course at the same temperature for purposes of comparison. The volume of the diluent gas is preferably at least twice that of the hydrocarbon gas. Usually, the ratio of volume of diluent gas to hydrocarbon gas is about three or four to one. The volume of diluent gas may be increased above this proportion without materially altering the character of the carbon, but for motives of economy, a volume of diluent gas greater than necessary should not be used. I prefer to use a diluent ratio of not over six volumes of diluent gas to one volume of hydrocarbon gas, nor below about twice that of the hydrocarbon gas.

By the decomposition of the run gas in the retort 1, solid carbon particles are formed together with hydro en gas. The hydrogen is swept along with t e stream of gases out of the retort 1. The recoverable carbon is ention of the retorts 1 and 30 by closing the valves 26, 27, 36 and 38, and a shut-off valve 43 in the outlet 2. Fuel and air are then su plied through the conduit 18 to blast t e checkerwork 14 b a hot blast, in the manner described for the eating up of a cold retort. As stated above, in such case, the cap valve 20 is opened and the mixture of fuel and air pass upwardly through the checkerwork 14 and highly heats the same. When the checkerwork 14 has thus been brought to the pro er temperature, the introduction of combusti le mixture through the conduit 18 is discontinued, the cap valve 20 is closed and the normal flow of run gas, residual gas and combustion products into the passage 19 and thence through the mixing chamber and through the checkerwork 14 is maintained until such operation of the apparatus must be again interrupted. The residual gas from which the entrained carbon particles are separated in the chamber 7 is discharged through the pipe 44. If a portion of this residual gas is to be used, as for instance, as a fuel or as a cheap source of hydrogen, the valve 45 may be opened to deliver a portion or all of the residual gas to the place where it is to be used. A branch 46 is provided for conducting the residual gas which is not thus used into the container 25.

It will be apparent that by my improved process the advantages of the Spear process for manufacturing carbon black may be in large measure retained, since the hot combustion products supplied from the retort 30 are mixed with the residual gas and the run gas to highly heat the same as they enter the retort 1. This provides for efliciency in the production of carbon black, since the period during which flow of the mixture of run gas and diluent gas through the retort 1 may be maintained is substantially lengthened. It is obvious not only that the hotblasting of the checkerwork 14 is a waste of time inasmuch as the quantity of carbon black produced by a retort'l in a twenty-four hour period is reduced; but it is also obvious that the fuel used for hot blasting the checkerwork 14 does not enter into the yield of carbon black. Therefore, my improvement in the process of producing carbon black, which rej work, 14 mustbeihot .blastedis a distinct adv'ance Iin-the'eficien I with which carbon be 1 On the other hand, ualjgas for dilutin the run resultsin the production o a carbon flick which approac esin its characteristics i the carbon black which is produced by the Spearand Moore process describedinapphcation Serial No; 300,131, filed August 16, 1928. It is apparent, therefore, that in accordance with my' im roved recess, the advanta es of both the bpea'r an Moore process and t e 7 ferred embodimentsof o a which comprises mixing a hydrocarborafias rocess are obtained. a y e I have described in detail the reinvention an the referred manner of the same,'it at theinvention is not and practiced within the-scope of the followa ,1. The process e; producing carbon black be decomposed with amixtureof a to uent gas consisting principally of the gaseous decomposition products obtained from the decomposition of a previously quantity ,of a hydrocarbon gas and a diluent as consistingprincipally-of the com ustion products obtained from the combustion of i fuehdecom the at a high tem-' perature to yiel solid-carbon Egrticles, and

se the carbon particles mthegaseou decomposition roducts. 2. The process 0 producing carbon black, .which comprisesmi'xing ahy ngas to be'decomposed "with 1M twice its vol [ume of a of'a diluent consisting principallad' off the gaseous drompodtion products tained from the decomposition of apreviousl treated quantity of a hydrocarbon gas an adiluent gas consistin princi- T pally of thegaseous combustion ucts ob- "tained 'from' the combustion of el, decomi V yield solid carbon particles, and separating 1 the carbon'particles from the gaseous decomro np r 1 a '3. The process'ot producing carbon black,

I zfwhich comprises-mixing the mixture at ahigh temperature to roducts a hydrocarbon gas If decomposed with a mixture of a diluent principally of the gaseous deperature of thehydrocarbon gas consisting a principallyof nitrogenand carbon dioxide,

' f passing the mixtureover extensive hot congmftact surfaces so as to decompose. the hydrm ;.-ca rbon gas andyield solid carbon'particlea and separating the carbon particles from the gaseous decomposition products.

4. The process of producing'carbon black, which comprisesmixinga hydrocarbongas drocarbon gas an nets 0 g the second diluent gas constituting from 20 the from the decomposition of a previously treatparticles from the tobe aeem osaw'ie ficmtwotosixtimes its volume of a mixture of a diluent gas consisting principally of the gaseous decomposition products obtained from the decomposition of a previously treated. quantity or a' hydroca bonand a diluent gas consisting princi a y of the gaseous combustion roducts o tained fromthe combustion of ous decomposition roducts.

5. The process 0 producing carbon black,

which comprises mixing r m 0 six esto be decomposed with its volume of a mixture of a diluent gas consisting principally of the gaseous decomposition roducts obtained from the decomposrtion 0 a previouslg treated quantity of a byn f th a diluent co rinci a o egaseouscom ustionp p Btaiiied from the combustion of fuel,

to 80 percent of the mixture of diluent gases,

decomposing the at a high tempera- .ture to yiel arating the carbotgsiarticles from the gaseous 7 solid carbon particles, and sepdecomposition p ucls.

7 6. .The proces; of producing carbon black, which: comprises burning a fuel, mixing the gaseous productsaof combustion before subd'antial 10$ of heat therefrom has occurred with a diluent gas consisting principally of gaseous decomposition products obtained ed quantity of a hydrocarbon gas and a hydrocarbon gas to be decomposed, the hydrocarbon gas being at a relatively lower temperature than the products of combustion prior-to mixing, passing the hot over extensive hot contact surfaces so as to decompose the hydrocarbon gas and yield solid carbon particles, and separating the carbon gaseous decomposition products.

7. The process ofproducin carbon black,

which comprises burning a 7 el to produce hot combustion min'ng the hot 'combustion gases with hydrocarbon gas to be decomposed and the gaseous decomposition products obtained from the decomposition of V r a previously treatedquantity of a hydrocarg {CQmPOSItIOII products obtained'from the'debe g? composition of a previousl treated quantity 5; o f-.iahydrocarbon a diluent gas at r :fatemperature above the decomposition temn gas, further heating the mixture so as to decompose the hydrocarbon gas and yield solid carbon particles and separating the carbon particles from the products.

8. The process which comprises mixing a hydrocarbon gas gaseous decomposition to be decomposed with at least twice its volume of a diluent gas consisting principally plh ducing carbon black, 7

products obtained from the decomposition of a previously treated quantity of hydrocarbon gas and the gaseous combustion products obtained from the combustion of fuel, passing the mixture over extensive hot contact surfaces so as to decompose the hydrocarbon gas and yield solid carbon particles, separating the carbon particles from the gaseous decomposition products, and hot blasting the contact surfaces from time to time to restore high temperature of the same.

In testimony whereof I have hereunto setmy hand.

CARROLL MILLER. 

